The present invention relates to a waterproof lens-fitted photo film unit. The present invention relates also to a waterproof ring, especially a waterproof ring for use in a waterproof case of the waterproof lens-fitted photo film unit.
The lens-fitted photo film units, which are preloaded with film and provided with simple photographic mechanisms, are widely used in general, because of handiness and low prices. Also, waterproof lens-fitted photo film units (hereinafter referred to as waterproof film units) have been brought into markets. The waterproof lens-fitted photo film unit is encased in a waterproof casing having a watertight structure, and permits operating it from outside the waterproof case for photography, so it is usable in the water.
An exemplary of the waterproof lens-fitted photo film unit is disclosed in Japanese Laid-open Patent Application No. 5-188457, wherein a waterproof case covers up a unit body configured substantially equivalent to a conventional lens-fitted photo film unit. In terms of handling properties in the water, a relatively large operation member is provided on a front side of the waterproof case, such that rotating the operation member causes a releasing member, that is provided inside the waterproof case, to press a shutter button of the unit body. Since the operation member is provided on the front side of the waterproof case, the positions the photographer""s fingers holding the waterproof lens-fitted photo film unit are so limited that the fingers are prevented from entering the photographic field and being photographed. Besides, shutter-releasing is done without fail just by sliding the finger on the front surface of the waterproof case.
The operation member is coupled to the releasing member through a rotary shaft that is put through a front wall of the waterproof case. The releasing member is bent around to reach a top side of the unit body, so the tip of the releasing member is located on the shutter button that is provided on the top side of the unit body. When the operation member is pushed down and rotates, the releasing member rotates, and the tip presses the shutter button to take a photograph.
To provide a space for allowing the tip of the releasing member to move is provided on the top side of the above conventional waterproof lens-fitted photo film unit, a corresponding part of a top wall of the waterproof case is protruded upward. The protrusion of the top side of the waterproof case worsens the appearance.
As an example, the waterproof case consists of a case main body for containing the lens-fitted photo film unit, and a lid for closing an opening formed through the case main body. A gasket ring is fitted in a gland formed around a rim of the opening of the case main body,. After the unit body is inserted in the case main body, the lid is put over and fixed to the opening of the case main body. Then the waterproof ring is nipped in a gap between the rim of the opening and the lid, so the opening is closed in a watertight fashion.
The waterproof ring is usually a rubber ring with a round sectional contour. However, the waterproof ring having a round section is apt twist when it is large enough for the opening that permits putting in and taking off the lens-fitted photo film unit or a camera through it, and thus disadvantageous in assembling. Moreover, since the waterproof rings have conventionally been formed individually by a metal mold, the conventional waterproof rings are pretty expensive. As a waterproof ring that overcomes these disadvantages, one having a substantially semicircular sectional contour is getting widely used these days. As having a flat surface, the waterproof ring with the approximately semicircular section (hereinafter referred to as the semi-cylindrical type waterproof ring) is inapt to twist and can be formed by cutting off from a semi-product of a cylindrical tubular shape, that saves the manufacture cost.
On the contrary, if a contact plane with which the flat surface of the semi-cylindrical type waterproof ring is brought into contact with is flat, pressures are distributed, so it is impossible to obtain a sufficient water shielding effect. For this reason, the contact plane has to be previously formed with a ridge. However, such a ridge must protrude substantially perpendicularly to a direction of pulling the metal mold off the case main body or another member in which the waterproof ring is fitted. Therefore, providing a ridge on the contact plane results in complicating the metal mold and thus rising the cost. Furthermore, even a little unevenness of the ridge on the contact plane will provide gaps between the ridge and the flat surface of the semi-cylindrical type waterproof ring, and lower the water shielding effect.
The present invention is made in view of the above described facts, and has an object to provide a waterproof lens-fitted photo film unit that is handy to operate and has a compact and smart shape.
The present invention further has an object to provide a waterproof ring that is hard to twist even with an increased ring diameter, and is manufactured at a low cost, as well as provides a sufficient water shielding effect even where the contacting portion is flat.
A waterproof lens-fitted photo film unit of the present invention is comprised of a unit body containing a photo film and photographic mechanisms, and a waterproof case that covers the unit body in a watertight fashion and is provided with a shutter release mechanism. The photographic mechanisms include a shutter blade, a shutter driving member for causing the shutter blade to make an open-close movement, and an arresting member for arresting the shutter driving member at a cocked position. The unit body is formed with an opening for exposing the arresting member at least partly. The shutter release mechanism comprises an operation member that is provided on the waterproof case, and a releasing member that acts on the arresting member through the opening in cooperation with the operation member being operated, to release the arrestment of the shutter driving member by the arresting member, thereby causing the shutter blade to open and close.
According to the present invention, the releasing member provided inside the waterproof case acts directly on the arresting member through the opening of the unit body, to activate the shutter driving member. Therefore, the structure is simplified as compared to the case where the shutter button is pressed by the releasing member, making it possible to provide a compact waterproof lens-fitted photo film unit at a low cost.
Providing the operation member on the front side of the waterproof case and making the releasing member act on the arresting member through the opening that is formed through the front side of the unit body enable locating the releasing member in a lower position than the top side of the unit body, so it is possible to achieve a better appearance without any protrusion on the top side of the waterproof case.
According to a preferred embodiment of the present invention, the operation member is affixed to an end of a rotary shaft that is inserted in a hole formed through the front wall of the waterproof case, and the releasing member is affixed to the other end of the rotary shaft. The rotary shaft is formed integrally with the operation member from plastics, and the above other end consists of a pair of arms extending in parallel to an axial direction. Each arm has an engaging claw protruding radially outward from its peripheral surface. As the pair of arms are inserted from the front side into the above hole while being bent toward each other, the engaging claws are engaged with inside surface of the front wall of the waterproof case by virtue of resiliency of the arms. Thereby, the rotary shaft is stopped from slipping off. The releasing member is affixed to tips of the arms. Then, the arms can bend only in a limited amount. Thus, it is possible to assemble these members without any cumbersome works such heat caulking or riveting.
A waterproof ring of the invention is characterized by comprising a curved surface portion and at least a flat surface portion, having a substantially semicircular sectional contour, and being provided with a ridge on the flat surface portion that is on the opposite side from the curved surface portion. According to this configuration, even if the member the waterproof ring is brought into contact with is flat, contact pressure is not distributed, so a reliable water shielding effect is provided. Because it is unnecessary to provide a ridge on the member in which the semi-cylindrical type waterproof ring is to be mounted, the member becomes easier to form, so it is possible to cut the manufacturing cost while improving reliability on the water shielding effect.
Shaping the curved surface portion to have a sectional contour that forms an arc with a constant radius, and locating a center of the arc at a summit of a sectional contour of the ridge, the waterproof ring keeps a constant thickness inside a gap in which the waterproof ring is nipped, even if the waterproof ring turns around. Thus, water shielding effect is stabilized.
Shaping the ridge of the waterproof ring to have an arc-shaped sectional contour at least around the summit contributes to improving assembling adaptability in addition to the above effects, because it becomes unnecessary to fix the inserting direction of the waterproof ring.